I am working on a 1968 Dart GTS 4 speed car. The car came to me in pieces and I am slowly putting it back together. The car has a center console mounted tach, and I need to wire it correctly. The tach has 4 wires coming out of the back with two molded plugs. One single wire plug (green) I know goes to the coil. The second plug has three wires. Orange (light) black (ground) and Violet ? My wiring diagram does not have a tach on it. I am thinking the violet wire is a power wire, but I am not sure. Anyone know what the violet wire is for?